1. Field of the Invention
The present invention relates to polymers and copolymers of indene and more particularly to polymers and copolymers of indene grafted on to elastomeric chains containing double bonds and bearing reactive sites, and to the processes for their production.
It is known that cationic polymerisations can be initiated by carbonium ions formed by the reaction of a metal halide with an alkyl halide such as an alkyl chloride. If a halogenated polymer is used instead of the alkyl chloride, a polymer is obtained containing carbonium ions which can initiate the polymerisation of a suitable monomer, which can, if necessary, be grafted in its turn on to the elastomer chain.
These reactions have been the subject of numerous studies, notably by reason of the importance of the copolymers obtained which can be, according to the elastomers and the monomers selected, thermoplastic elastomers.
2. Description of the Prior Art
In the "Journal of Polymer Science" (Part. A-1, 4,1665 (1966) the grafting by cationic polymerisation of styrene on to chlorobutyl rubber, in cyclohexane solution is described; the catalyst used is SnCl.sub.4, and the reaction temperature is 20.degree. C. The percentage of grafting can be increased by raising the concentration of styrene and of SnCl.sub.4 or by the addition of a polar solvent such as nitrobenzene. The concentration of chlorinated elastomer is without influence on the grafting but plays a role in the degree of polymerisation.
British Pat. No. 1,174,323 provides a process of grafting numerous monomers by cationic polymerisation on various halogenated elastomers, the catalyst being of the formula Al(M).sub.2 R in which M represents an alkyl radical and R is a halogen or hydrogen; the co-catalyst is the halogenated polymer itself. According to the description of this patent, the monomers usable are notably styrene and its derivatives, as well as a large number of monomers polymerisable by the cationic route, mentioned in a general treatise to which reference is made.
The process of British Pat. No. 1,174,323 enables the production of the graftings described with certain monomers, notably styrene, which permits the obtaining of interesting results, but many of the monomers mentioned cause the formation of polymers which are either brittle or of low molecular weight or difficult to use, as is the case with propylene or the higher alkenes, .alpha.- or .beta.-methylstyrene, or do not enable polymerisation to be achieved, such as ethylene, diphenyl-1,1-ethylene, stilbene or indole, among others.
The teachings of the aforementioned patent hence do not enable the syntheses provided to be carried out from all the constituents that it mentions.